(a) Field of the Invention
The present invention relates to an acrylic impact modifier having a multilayered structure, which is prepared by multistep emulsion polymerization, a method for preparing the same, and a thermoplastic resin comprising the polymer as an impact modifier
(b) Description of the Related Art
A polycarbonate resin is widely used for molding products of automobiles and electric/electronic products due to its superior impact resistance, electrical properties, and heat resistance. However, the polycarbonate resin has a high melt viscosity and poor molding property. Moreover, its impact resistance is highly dependent on thickness, and its chemical resistance is also poor. Accordingly, PC/ABS, an alloy of PC and acrylonitrile-butadiene-styrene (ABS), is used to compensate for the high melt viscosity of polycarbonate (PC), or a resin such as polybutylene terephthalate is mixed with PC to compensate for its chemical resistance.
European Patent Publication No. 465,792 discloses a polymer comprising a rubbery acrylate monomer, which improves impact resistance of polycarbonate and offers uniform coloring property when used together with a pigment, and a resin composition prepared by blending the polymer with polycarbonate. However, such a modified polycarbonate does not have enough impact resistance. Although the acryl-based polymer can be used as an impact modifier in thermoplastic resins, such as a polybutylene terephthalate resin and a polyvinyl chloride (PVC) resin, as well as in polycarbonate, the balance of impact resistance and coloring property is insufficient, as yet.